[Index] Handle shorthand if let/closure captures in local rename
Update rename to pull the outermost-declaration so that references are correctly found.
Rather than keeping suppressed locations in the current parent, keep
them for the whole index. Local rename starts the lookup from the
innermost context it can, which could be a closure. In that case there
is no parent decl on the stack and thus no where to store the locations
to suppress. We could have a specific store for this case, but there
shouldn't be that many of these and they're relatively cheap to store
anyway.
Resolves rdar://104568539.
(cherry picked from commit 4cc7167b603f37ce2cfb97b945478bf8aa45f6d8)
